| Rank | Country | Railways |
| Tokelau | void |
| Tonga | void |
| Trinidad and Tobago | void |
71 | Tunisia | total: 2,153 km standard gauge: 471 km 1.435-m gauge narrow gauge: 1,674 km 1.000-m gauge (65 km electrified) dual gauge: 8 km 1.435 m and 1.000-m gauges (three rails) (2006) |
23 | Turkey | total: 8,697 km standard gauge: 8,697 km 1.435-m gauge (1,920 km electrified) (2006) |
66 | Turkmenistan | total: 2,440 km broad gauge: 2,440 km 1.520-m gauge (2006) |
| Turks and Caicos Islands | void |
| Tuvalu | void |
83 | Uganda | total: 1,244 km narrow gauge: 1,244 km 1.000-m gauge (2006) |
13 | Ukraine | total: 22,473 km broad gauge: 22,473 km 1.524-m gauge (9,250 km electrified) (2006) |
| United Arab Emirates | void |
17 | United Kingdom | total: 16,567 km broad gauge: 303 km 1.600-m gauge (in Northern Ireland) standard gauge: 16,264 km 1.435-m gauge (5,361 km electrified) (2006) |
1 | United States | total: 226,612 km standard gauge: 226,612 km 1.435-m gauge (2005) |
| United States Pacific Island Wildlife Refuges | void |
73 | Uruguay | total: 2,073 km standard gauge: 2,073 km 1.435-m gauge note: 461 km have been taken out of service and 460 km are in partial use (2006) |
44 | Uzbekistan | total: 3,950 km broad gauge: 3,950 km 1.520-m gauge (620 km electrified) (2006) |
| Vanuatu | void |
106 | Venezuela | total: 682 km standard gauge: 682 km 1.435-m gauge (2006) |
64 | Vietnam | total: 2,600 km standard gauge: 178 km 1.435-m gauge narrow gauge: 2,169 km 1.000-m gauge dual gauge: 253 km three-rail track combining 1.435 m and 1.000-m gauges (2006) |
| Virgin Islands | void |
| Wake Island | void |
| Wallis and Futuna | void |
| West Bank | void |
| Western Sahara | void |
| World | total: 1,370,782 km (2006) |
| Yemen | void |
70 | Zambia | total: 2,157 km narrow gauge: 2,157 km 1.067-m gauge note: includes 891 km of the Tanzania-Zambia Railway Authority (TAZARA) (2006) |
55 | Zimbabwe | total: 3,077 km narrow gauge: 3,077 km 1.067-m gauge (313 km electrified) (2006) |